An American scientist recently sparked a trans-Atlantic tempest by offering Britain advice on making tea.

Bryn Mawr College chemistry professor Michelle Francl said one of the keys to the perfect cup of tea is a pinch of salt. The tip is included in Francl's book "Steeped: The Chemistry of Tea," published Wednesday by the Royal Society of Chemistry.

Francl said adding a small amount of salt - not enough to taste - makes tea seem less bitter because "the sodium ions in salt block the bitter receptors in our mouths."

The salt suggestion drew howls of outrage from tea lovers in Britain, where popular stereotype sees Americans as coffee-swilling boors who make tea, if at all, in the microwave.

The U.S. Embassy in London intervened in the brewing storm with a social media post reassuring "the good people of the U.K. that the unthinkable notion of adding salt to Britain’s national drink is not official United States policy."

"Let us unite in our steeped solidarity and show the world that when it comes to tea, we stand as one," said the tongue-in-cheek post. "The U.S. Embassy will continue to make tea in the proper way - by microwaving it."

The embassy later clarified that its statement was "a lighthearted play on our shared cultural connections" rather than an official press release.

Is salt in tea a taboo?

In fact, salted tea is not taboo elsewhere in the world. The practice of adding salt and other elements can be dated back in history across China, where tea plantations have long existed.

Ancient people in the Tang Dynasty (618-907) liked to add salt and pepper to their tea, accompanied by various other condiments, such as orange peel and ginger. Therefore, utensils were needed to store and hold these seasonings.

This gilded silver salt tray unearthed from the Famen Temple in Fufeng, Shaanxi Province is one such utensil used for holding salt and pepper. The historical artifact provides insights into the tea culture of the Tang Dynasty and highlights the importance of condiments in tea preparation.

Salt added to tea is something the Tibetans still do when making yak butter tea. Very much an acquired taste, butter tea is made from strong tea, yak butter, water, and salt, and has a slight cheese-like flavor. In the high and oxygen-deprived Qinghai-Xizang Plateau, no beverage can replace the status of butter tea. It is consumed throughout the Xizang Autonomous Region and plays an important ceremonial role in welcoming guests.

A similar tea beverage favored by people in Inner Mongolia is tsutaitsai. Many locals drink it hot in the morning, made with black tea and fresh milk with salt, along with other condiments to enhance the flavor. The way of preparing the drink can also vary, and today you can purchase it in an instant packet form.

Lei cha, or ground tea, is a tea-based beverage from southern China that belongs to the Hakka culture. Making it is a laborious process that takes hours. Traditionally, tea, other herbs and even crispy rice and nuts were pounded with a large mortar and a long stick made from a guava tree. Lei cha is also considered by many as an alternative kind of soup.

As a soup or with salt, tea-drinking traditions in China have evolved through the ages. It’s not only the taste of the tea but its vast variations that make people fall in love with the beverage across the globe.

(Story includes material sourced from AP.)